Base Theme & Sub Theme in Drupal

* Sub theme inherits the parent theme's resources
* file to declare the   "base theme = parent_themename"

* All Stylesheets, Javascripts, features, template.php functions, page - block - node and other template (.tpl.php) files ... etc are inherited from the parent theme.
* If you want to override these files, you can create in the subtheme directory.
* logo, favicon, regions & theme settings are no inherited, unless you can copy these declarations from the parent theme.